The present invention relates generally to a transmission line. More particularly, the present invention relates to a rigid coaxial transmission line with enhanced broadband capabilities.
With the advent of digital television, it has become increasingly important that transmission lines carrying broadcast signals to broadcasts antennas convey the signals with minimal attenuation and signal distortion. Due to zoning constraints, economic, and other pressures, broadcasters have devised upon multiplexing different station signals onto a single broadcast antenna to increase signal throughput. The multiplexing of various broadcast signals onto a single transmission line increases the frequency requirements of the transmission line.
Conventional transmission lines of the broadcast caliber are usually coaxial in nature and very long, being fabricated from joining several smaller coaxial transmission lines together. The joints formed at the junction of the smaller lines unavoidably create flange joints, whereby it is well known that these flange joints generate reflections of the propagating signals in the line. Additionally, to maintain the necessary separation between the inner conductor and the outer conductor of the coaxial line, series of insulating supports are interspersed within the line at specified locations. These insulating supports are usually solid in the form and are also well known to affect the characteristics of the signal and generate reflections along the line.
Therefore, these flange joints and insulating structures detrimentally affect the broadband capabilities of the transmission line. Various attempts have been made in this discipline to mitigate these effects. However, these attempts typically require complicated or significant re-engineering of the transmission line.
Therefore, there has been a long standing need in the transmission line community for a simply configured broadband rigid coaxial transmission line having reduced reflections.
The foregoing needs are met, to a great extent, by the present invention, wherein difficulties in the prior art are mitigated by using a specially formulated segmentation and a specially shaped insulating support. These and other advantages of the invention are discussed in greater detail below.
In accordance with one embodiment of the present invention, systems and methods for an improved transmission line is provided by joined segments of coaxial transmission lines, the segments having lengths xcex94L(n) according to:
xcex94L(n)=K((nxe2x88x921)/N)xcexcfor n=1. . . N, 
and
Lg(n)=Lxe2x88x92xcex94L(n) for n=1. . . N, 
n being an arbitrary index, N being a total number of line sections in the line run, L being a length of the longest section in the line run, Lg(n) being a length of a segment at index n, and K and xcexc being adjustable line constants, where xcexc ranges substantially around 1-1.2, and a plurality of insulating supports are arranged within the segments, a first support position a(n) being substantially located according to
a(n)=Axe2x88x92xcex94L(n)/D, 
and a second support position b(n) being substantially located according to
b(n)=Bxe2x88x92xcex94L(n)/E, 
and a third support position c(n) being substantially located according to
c(n)=C, 
where A, B, and C are empirically determined constants, and D=2 and E=3.
In accordance with another embodiment of the present invention, a coaxial transmission line insulating support is provided from a cavitied puck of electrically insulating material having sets of rotationally symmetric exterior voids at the perimeter of the puck, the puck having a center conductor hole and sets of rotationally symmetric interior voids, the interior voids being arranged between the center conductor hole and the exterior voids, wherein a centroid of the interior voids are substantially located at the median line between pairs of adjacent exterior voids.
There has thus been outlined, rather broadly, certain embodiments of the invention in order that the detailed description herein may be better understood, and in order that the present contribution to the art may be better appreciated. There are, of course, additional embodiments of the invention that will be described below and which will form the subject matter of the claims appended hereto.
In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of embodiments in addition to those described and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein, as well as the abstract, are for the purpose of description and should not be regarded as limiting.
As such, those skilled in the art will appreciate that the conception upon which this disclosure is based may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.